The aim of this Center is to provide scientific resources for studying the nutritional, endocrine, and metabolic aspects of HIV infection in chronic drug users of different ethnicities (Caucasian, Hispanic, and African-Americans) who are using various types of illicit drugs. HIV-positive drug users face a unique set of issues and challenges that may exacerbate their illness, including poor nutrition, inadequate medical care, difficulties adhering to complicated therapeutic regimens, and the use of specific drugs known to impair metabolic function. Investigation of the overall nutrition, endocrine, and metabolic effects of HIV infection in the general HIV-positive population, however, seldom extends to the drug using population, a group in which 50% of new HIV infections occurs. This Center will consist of 6 Cores: Administrative, Developmental, Drug User Resources, Nutrition and Metabolism, Endocrine, and Epidemiology/Biostatistics. The Center will build upon an existing infrastructure of studies in drug users at four East Coast institutions (Tufts University School of Medicine in Boston, Massachusetts; Brown University School of Medicine in Providence, Rhode Island; Johns Hopkins Medical Institutions in Baltimore, Maryland; and the New York Academy of Medicine, in New York City, New York). Tufts has developed programs in specific nutrition and metabolic aspects of HIV infection and has a research program in Hispanic drug users with and without HIV. Brown University has developed expertise in conducting research among specialized populations, including injection drug users, substance abusing women, and incarcerated drug users. Johns Hopkins has research in endocrine disorders among drug users with HIV, and has active longitudinal studies of African-American injection drug users. The New York Academy of Medicine's Center for Urban Epidemiologic Studies has several ongoing research studies related to HIV infection in drug using populations. The proposed Center will combine the complementary resources and expertise that exist at each of the collaborating sites to develop a new research program that will focus on the nutritional, metabolic, and endocrine abnormalities in HIV-positive and HIV-negative drug users.